Memory media in the sense of the invention are used for holding ready various data, for example applications for various areas of use, or also media data such as photographs or films. The memory medium is designed to be portable and can have an exterior design as a flat card or alternatively as a token.
The memory medium has a memory area (mass memory) and a memory management system, e.g. a memory controller or a system of several coupled memory controllers through which the memory area is managed. The data are stored in the memory area. The memory area can be structured in partial memory areas. The memory management system provides a set of commands containing a plurality of pre-defined commands by means of which the tasks of the memory management can be carried out, such as, for example, reading (READ) or writing (WRITE) in the memory area, opening of parts of the memory (OPEN), or setting and canceling a write protection for the memory area. Some commands are kept free as reserved commands for possible tasks of the memory management that are to be configured later.
In principle, the memory area can be realized in any suitable—preferably electric—memory technology, in particular as a flash memory, but also as RAM, ROM or EEPROM.
Specific commands are specified, for example, in different interface standards that the memory medium meets. Examples for interface standards for memory media are SD (Secure Digital Memory Card), MMC (Multi Media Card), USB (Universal Serial Bus), SCSI (Small Computer System Interface). In the following, a memory medium is examined in part with reference to the example of the interface standard SD. The same applies analogously to memory media according to other interface standards.
Memory media according to the SD interface standard are described, for example, in “SD Specifications, Part 1, Physical Layer Specification” (http://www.sdcard.org) (hereinafter referred to as “SD-Spec”). The SD memory medium comprises a set of pre-defined commands. They permit the manufacturer, for example, to set write protection bits (commands CMD28, CMD29, CMD30) in order to protect data against being deleted. The SD memory card can be locked by a host by means of a “card lock” with the command CMD16. The lock can be disabled again with a password. A mechanical write protection tab offers another option for protecting data against deletion.
According to the SD-Spec, some commands, e.g. CMD60 et seqq., are reserved as so-called “manufacturer specific commands”.
Frequently, commands are divided into a command type part, an argument part (sometimes also referred to as address part) and a data part. The data part contains a data body part (body) and optionally a routing information part (header) usually preceding the data body part.
In a conventional command such as, for example, write, the command type “write” is implemented in the command type part, the argument part (address part) specifies at which logical address in the memory area the write access is to be carried out, and the data part, more specifically the data body part, specifies what is to be written.
Optionally, the memory medium has a microprocessor, the task of the memory management optionally being carried out by the microprocessor. Examples of such portable memory media are smart cards equipped with a microprocessor and memory cards equipped with a memory controller. If the portable memory medium is used, for example, in the field of mobile radio, the portable memory medium can be designed, for example, as a smart card with a security module for using a terminal device (e.g. mobile phone) in a mobile radio network, or be integrated into such a smart card. The smart card is, for example, a SIM card for the GSM system or a USIM card for the UMTS system or a similar smart card. Optionally, the portable memory medium is designed as a pay-TV card for using pay TV, or is integrated into such a pay-TV card. Optionally, the portable memory medium is a secure flash card with an integrated smart card or a smart card integrated into a secure flash card, with the secure flash card comprising, as a memory management system, a flash controller superordinate to the smart card.
The portable memory medium can be read and written into by means of a terminal device. For example, a PC (personal computer), a mobile terminal device for a mobile radio network, e.g. a mobile telephone, PDA, smartphone etc., or a set-top box for pay TV is provided as a terminal device. In the case of a portable memory medium designed as a secure flash card or smart card integrated into a secure flash card, a mobile terminal device such as, for example, a mobile telephone, PDA or smartphone etc. can be provided as a terminal device. The terminal device has an operating system, for example a PC operating system or an operating system for mobile terminal devices, such as, for example Microsoft Windows, Microsoft Windows Mobile, Linux, Symbian or the like.
It can be desirable, especially for partial memory areas in the memory area in which applications are stored, that a user of the memory medium is unable to make any modifications so that applications are not inadvertently deleted, for example. However, it may be desired that other data are also protected against inadvertent or intentional deletion or modification.
Many PC operating systems make it possible to create different partitions in order to divide memory areas and to thus create, in the form of protected partitions, partial areas protected against the deletion of data. In many mobile terminal devices, the operating system does not offer the option of creating partitions on a memory medium used therein.
WO 2008/058741 describes a method for access to a memory medium with a memory area and a controller for managing the memory area in which data streams containing routing data are transmitted to an additional module, for example, a specially protected microprocessor or partial area of the controller.
Document WO 2008/058705, which is considered the closest state of the art, describes a memory medium with a memory area, and a memory management (controller) for managing the memory area, wherein different options for access to the memory area are provided. In the case of an access to the memory area via the memory management, specifying an address in the memory area, the memory management, in accordance with the address, forwards the access directly to the memory area, or to an additional module, which is a smart card microcontroller, for example. Different options for access are thus provided depending on the address specified during the access.
In the memory medium from WO 2008/058705, the corresponding addresses or address ranges compulsorily lead to an access being redirected to the additional module.
In some cases, a more flexible configuration of the memory management would be desirable, which would permit, for example, the creation of partitions on the memory medium irrespective of the operating system of a terminal device used for reading or writing on the memory medium, in order thus to protect data against deletion.
Conventionally, the memory area of a memory medium can be switched between two different memory configurations, i.e. “write access permitted” and “write access not permitted” when the write protection is set (enabled) and canceled (disabled) by means of a pre-defined command, e.g. in accordance with the SD Spec. In this case, the write protection comprises the entire memory area, or optionally partial areas, if the operating system of the terminal device in which the memory medium is operated supports a partitioning of the memory area.